Examples of repressor proteins are lac repressor that inhibits the expression of lacoperon in E. coli. Another is MetJ, a methionine repressor of metoperon.

Repressor proteins are influenced by the presence of other molecules, such as corepressors and inducers. Corepressors are molecules that bind and activate repressors. Inducers, on the other hand, bind and regulate repressors by inducing the latter to undergo conformational change thereby decreasing binding affinity to the operator.